Heating system for railway cars and the like



Oct. 11, 1932. w. G. HARTWIG 1,881,546

HEATING SYSTEMTOR RAILWAY CARS AND THE LIKE Filed Jan. 23, 1932 Patented Oct. 11, 1932 UNITED STATES PATENT OFFICE WILLIAM G. HARTWIG, OF CHICAGO, ILLINOIS, ASSIGNOR 'IO RAILWAY UTILITY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS HEATING- SYS'IEM FOR, RAILWAY CABS AND THE LIKE Application filed January 23, 1932. Serial No. 588,293.

., dium to the heater is controlled by a relay,

which in turn is controlled by a thermostat. It is important with respect to the relay, and more particularly with respect to the thermostat to reduce as far as possible sparking and the flow of excess current, particularly on the opening of the circuit. It is also important to provide against excess current through the controlling instrumentalities in case of the grounding of the coil of a main switch or contactor. A further circumstance which must be guarded against so far as practicable is the tampering wit-h the apparatus particularly by the car crew. In prior wiring of such systems, the cutting of the wires leading to the thermostat leaves the contactor circuit and consequently the heating circuit closed and therefore it has been not uncommon for a member of the crew of a car to cut the wires beneath the thermostat so as to keep the car at a higher temperature. It is the object of the present invention to mini mize the above mentioned objections to systems of this character.

In the accompanying drawing I have t 1 shown diagrammatically the improved circuit of my invention.

In the drawing the line from which the supply of electric current is derived is indicated at 1, the contactor or main switch at 2, and the heater supplied from the line at 3. These elements of the system may be of any desired or approved type. The coil of the contactor is indicated at -4 and it is supplied with current from the line through a line resistor 5. wiring 6, movable and stationary contacts 7, 8 and wire 9. The other end of the coil 4 is grounded through wire 10, a balance resistance 11 and wires 12, 13. A shunt circuit about the coil 4 is provided, the shunt being controlled by a switch, the contacts of which are closed prior to the separation of the contacts 7, 8 to open the circuit of the contactor coil 4, and remain closed until the closing of the contacts 7, 8. Both these pairs of contacts, towit, those controlling the contactor coil circuit and those controlling the shunt are controlled by a relay coil 14, which in turn is controlled by the thermostat. In the specific embodiment of the invention illustrated, one of the contacts 15 of the shunt is formed with the movable contact 7 of the contactor coil circuit, the two contacts 7, 15 forming with their barrel or hinge member 16 a pivoted or swinging element which is electrically connected to wire 6, above mentioned. The other contact of the pair controlling the shunt circuit is the pivoted armature 17 of the relay. When the relay coil 14 is deenergized the armature and the swinging element, above described, occupy the position shown in the drawing in which contact 7 is engaged with contact 8 and the contactor coil is supplied with energizing current. At the same time the armature 17 is out of engagement wit-h contact 15. When the relay coil 14 is energized, it, of course, attracts its armature 17 which first engages contact 15, thus closing the shunt circuit. The further movement of armature 17 under the attraction of the relay coil separates contacts 7 and 8 and thus deenergizes the contactor coil. Preferably, the armature 17 is provided with an insulated angular member 18 which, when the armature drops, engages the upper face of contact member 15 so that the weight of the armature serves to firmly hold the contact 7 in engagement with fixed contact 8.

The shunt circuit about coil 4 is completed to the balance resistance by the wire 19. Thus when the shunt contacts are in engagement a path for the current is created from wire 6 through contact 15, armature contact 17, wire 19, balance resistance 11, wire 12 and wire 13 to ground.

One terminal of the relay coil 14 is connected by wire 21 to the end of the balance resistance adjacent the contacts just described. The other end of the relay coil is connected through wire 22, fuse 23 and test key 24 to the upper contact 25 of the thermostat. The lower thermostat contact 26 is connected to the ground wire 18 above mentioned. The relay coil is thus in parallel to the balance resistance, and when the temperature rises to the point for which the thermostat is designed, a branch or shunt circuit through the relay coil provided as follows: Through wire 21, relay coil 14', wire 22, fuse 23, test key 24c, the thermostat and to ground through wire-'13:

In order to reduce the current througlrthe thermostat, particularly at the time it Opens its circuit and at thesame time to assurethc feeble current in the relay coil required to hold the relay after it has'been raised toits attracted position, I provide a shunt circuit 35' containing. a relatively low resistance 36 about thepoint' of'union er the relay coilcircuit with the main switch and main shunt circuits. one. end .v and at the other is provided with a contactBT arranged to be engaged by contact 7 as the armature 1T approaches-its attracted position. Thus the main. portion of the cunrent which energized relay coil 14 to cause it to attract its armature is diverted through shunt circuit 35, so that only atceble cur rentlisflowin throu h the thermostat at the.

time it. breaks thecircuit.

WhileIha've shown and described a ther mometer typethermostat. it will be obvious that a. bimet ai ic or other thermostat. may be used; Asaninstance of a suitable proportioning of the resistances. of the several circuits offthe. system, the contactor or maiii switch may have a resistance: of 840 ohms, the balanceresistance, 225 ohms, the relay coil circuit 1200 ohms and. coil 36-, 50 ohms. It will be noted that the thermostat and the-main switchor contactor coil: are ground.- ed by the same: wire 13 from. which it follows that it both wires connected to the respective contacts ofthe thermostat are cut,

or ifthegroundzwireis cut, the contactor coil as well. as the relay coil is deenergi zcd so that the heating circuit. remains open. Ordinarily theWires-connected to. the contacts of thermostatsv of this. character are carried: to-

gether: through the back or supportv ofthe.

wiring,- sucln as a. member of the car crew,

to, dismantle the control by cutting the wires results in throwing oil the heat altogether until the apparatus 1s repaired.

Furthermore, a grounding or short-circuitlng or an. opemng of the coil 4 similarly ail ectsthe clrcuit through the relay coil and thermostat so that the latter are not sub ec-ted to ihjnriously heavy current. in any such Shunt 351s connected to wire 12 at event. It is also to be observed that sparkin between the contacts 7 and 8 upon their opening is avoided by the previous establishment of the shunt circuit.

I claim:

1. In a system for controlling the flow of medium to a heater, an automatic. electromagnetic switch comprising an operating coil, a shunt circuit about said coil, 9. source: of electric. energy, connections there i nomto said coil and shunt circuit, a pair of contacts in the coil circuit, a pair of contacts in the shuntcircu t, connections between movable members of said pairs of contacts: whereby onepair is open when the other is closed, a relay coil in series with both the operating coil andithe shunt circuit for opening. and closing, said pa rs of contacts, and a thermostat in series with said relay coil for controlling,"current. llow therethrough.

2 In a s' stemfor controllin i. the how of heating meoiinn to a heater, an automatic electromagnetic switch, comprising: an operating, coil, a: shunt circuit about said coil, a sourceoi electrical cnergy, connections there-- from to said coil and shunt circuit, a pair of contacts in the circuit of's id coil, a pair of contacts in said shunt circuit, connections between movable members of said pairs of contacts whereby one pairis open when the other is closed, {ll relay coil? inv series with both the operating coil and shunt. circuit for opening. and closin said pairs ot'contacts, a thermwstat in series with said relay coil: for controlling current flow therethrough, and a shunt circuit about said relay coil and thcrmostat.

5.v In asystcm for controlling. the low of" from to said coil and shunt circuit, a pair 0*? contacts 111. the circuit OfSZIlCl 0011, a pair of.

contacts in said shunt circuit, connections between. movable members of said pairs 01": contacts whereby one pair open when the other is closed, a relay coil in series with both the openatingzcoil and shunt circuit for openingiand'closing said pair-sot contacts, a thermostat in series with said relay coil for core trolling.- current flow thercthrough, and a shunt circuit about said relay coil and thermostat includinga balance resistor.

4. In a system for controllingthe flow of heating medium to a heater, an automatic. electromagnetic switch comprising an operating coil, a shunt circuit about said coil, means for opening. and closing said coil and shunt circuits, comprising a movable member common to both said circuits and a second movable member adapted to engage the first to close the shunt cir uit and. oper ate sa d li'rst movable member to open the coil circuit, a source of electric energy, connections therefrom to the first said movable member, a relay coil for operating the second movable member, in series with both said circuits, and a thermostat in series with said relay coil and controlling the flow of current therethrough.

5. In a system for controlling the flow of heating medium to a heater, an automatic, electromagnetic switch comprising an operating coil, a shunt circuit about said coil, means for opening and closing the coil and shunt circuits, comprising a movable member common to both said circuits and a second movable member adapted to engage the first to close the shunt circuit and operate said first movable member to open the coil circuit, a source of electric energy, connections therefrom to the first said movable member, a relay coil for operating the second said movable member, in series with both said circuits, a thermostat in series with said relay coil and controlling the flow of current therethrough, and a second circuit parallel to the circuit through said relay coil and thermostat and containing a balance resistor.

6. A system for controlling the fiow of heating medium to a heater as described in claim 5 in which the shunt circuit about the operating coil is closed before the operating coil circuit is opened.

7. In a system for controlling the flow of heating medium to a heater, an automatic, electromagnetic switch comprising an operating coil, a shunt circuit about said coil, means for opening and closing said coil and shunt circuit, comprising a movable member common to both said circuitsand a second movable member adapted to engage the first to close the shunt circuit and operate said first movable member to open the coil circuit, a source of electric energy, connections therefrom to the first said movable member, a relay coil for operating the second movable member, in series with both said circuits, a thermostat in series with said relay coil and controlling the flow of current therethrough, a low resistance shunt circuit about the thermostat and relay coil, and means for closing said shunt circuit after the relay and thermostat circuit is closed and maintaining it closed until after the thermostat opens said relay coil circuit.

8. In a system for controlling the flow of heating medium to a heater, an automatic, electromagnetic switch comprising an operating coil, a shunt circuit about said coil, a fixed contact for said coil circuit, a movable contact for the coil circuit, a source of electric energy, connections therefrom to said movable contact, a relay comprising a coil and an armature, the armature adapted when the coil is energized to engage said movable contact and first close the shunt circuit and then move said contact to open the coil circuit, the coil of the relay being in series both with the coil circuit and the shunt circuit, and a thermostat controlling the circuit of said relay coil.

9. In a system for controlling the flow of heating medium to a heater, an automatic, electromagnetic switch comprising an operating coil, a shunt circuit about said coil, a relay the coil of which is in series to both the coil circuit and the shunt circuit, a thermostat in the relay coil circuit, a low resistance shunt circuit about the relay coil and thermostat, a movable contact member, a source of electric energy and connections therefrom to said movable contact member, a relatively fixed contact with which the movable contact engages to close the circuit through the first mentioned coil, a second relatively fixed contact with which said movable contact engages to close the low resistance circuit about the relay coil and thermostat, and an armature for the relay coil adapted to engage said movable contact and thereby first close the first mentioned shunt circuit and thereafter open said coil circuit and close the shunt circuit about the relay coil and thermostat.

In testimony whereof, I have subscribed my name.

WILLIAM G. I-IARTWIG. 

